Workpiece handlers are commonly used in semiconductor manufacturing to transfer workpieces such as substrates (e.g., semiconductor wafers) through the various processes of manufacturing. Semiconductor processing equipment utilizes workpiece or substrate aligners to provide alignment functions and substrate identification functions during semiconductor processing. These workpiece or substrate aligners are generally mounted at one end (e.g. on a side) of a factory interface or equipment front end module. Manufacturers use aligners to “center find” and “position” substrates or carriers in a specific orientation to ensure process performance/uniformity is properly tracked.
Currently, aligners are either “center contact” or “edge/outer contact” type. Center contact aligners will work with any solid substrate or work piece such as wafers or carrier bases which may hold other substrates such as reticles. However, a center contact aligner will not work with a work piece that has a large opening or hole in the middle such as a. carrier shield. An edge/outer contact aligner is required to support the work pieces with a large hole in the center. FIG. 1 shows an edge/outer contact aligner 10 which can support either solid workpiece in the form of solid carrier base 12 or a shield 14 with an opening 16 therein. FIG. 2 shows a center contact aligner 20, which can process a solid carrier base 12 or wafer, but not the shield 14 having the large opening 16 therein because the center contact aligner 20 does not have a chuck 22 large enough to accommodate the opening 16 in the shield 14.
A problem with current edge/outer contact aligners is that they require an additional internal mechanism such as the lift pins 15 shown in FIG. 1 to lift the wafer or carrier off the aligner arm 17 so that it can be removed. This additional internal lifting mechanism creates particles and adds complexity and cost to the aligner design. It would be useful to provide an aligner that can align without an internal lifting mechanism and that is capable center contact alignment or edge/outer contact alignment utilizing a single aligner head design.